<?php

/**

 * Block support to enable per-section styling of block types via

 * block style variations.

 *

 * @package WordPress

 * @since 6.6.0

 */

/**

 * Generate block style variation instance name.

 *

 * @since 6.6.0

 * @access private

 *

 * @param array  $block     Block object.

 * @param string $variation Slug for the block style variation.

 *

 * @return string The unique variation name.

 */

function wp_create_block_style_variation_instance_name( $block, $variation ) {

	return $variation . '--' . md5( serialize( $block ) );

}

/**

 * Determines the block style variation names within a CSS class string.

 *

 * @since 6.6.0

 *

 * @param string $class_string CSS class string to look for a variation in.

 *

 * @return array|null The block style variation name if found.

 */

function wp_get_block_style_variation_name_from_class( $class_string ) {

	if ( ! is_string( $class_string ) ) {

		return null;

	}

	preg_match_all( '/\bis-style-(?!default)(\S+)\b/', $class_string, $matches );

	return $matches[1] ?? null;

}

/**

 * Recursively resolves any `ref` values within a block style variation's data.

 *

 * @since 6.6.0

 * @access private

 *

 * @param array $variation_data Reference to the variation data being processed.

 * @param array $theme_json     Theme.json data to retrieve referenced values from.

 */

function wp_resolve_block_style_variation_ref_values( &$variation_data, $theme_json ) {

	foreach ( $variation_data as $key => &$value ) {

		// Only need to potentially process arrays.

		if ( is_array( $value ) ) {

			// If ref value is set, attempt to find its matching value and update it.

			if ( array_key_exists( 'ref', $value ) ) {

				// Clean up any invalid ref value.

				if ( empty( $value['ref'] ) || ! is_string( $value['ref'] ) ) {

					unset( $variation_data[ $key ] );

				}

				$value_path = explode( '.', $value['ref'] ?? '' );

				$ref_value  = _wp_array_get( $theme_json, $value_path );

				// Only update the current value if the referenced path matched a value.

				if ( null === $ref_value ) {

					unset( $variation_data[ $key ] );

				} else {

					$value = $ref_value;

				}

			} else {

				// Recursively look for ref instances.

				wp_resolve_block_style_variation_ref_values( $value, $theme_json );

			}

		}

	}

}

/**

 * Render the block style variation's styles.

 *

 * In the case of nested blocks with variations applied, we want the parent

 * variation's styles to be rendered before their descendants. This solves the

 * issue of a block type being styled in both the parent and descendant: we want

 * the descendant style to take priority, and this is done by loading it after,

 * in the DOM order. This is why the variation stylesheet generation is in a

 * different filter.

 *

 * @since 6.6.0

 * @access private

 *

 * @param array $parsed_block The parsed block.

 *

 * @return array The parsed block with block style variation classname added.

 */

function wp_render_block_style_variation_support_styles( $parsed_block ) {

	$classes    = $parsed_block['attrs']['className'] ?? null;

	$variations = wp_get_block_style_variation_name_from_class( $classes );

	if ( ! $variations ) {

		return $parsed_block;

	}

	$tree       = WP_Theme_JSON_Resolver::get_merged_data();

	$theme_json = $tree->get_raw_data();

	// Only the first block style variation with data is supported.

	$variation_data = array();

	foreach ( $variations as $variation ) {

		$variation_data = $theme_json['styles']['blocks'][ $parsed_block['blockName'] ]['variations'][ $variation ] ?? array();

		if ( ! empty( $variation_data ) ) {

			break;

		}

	}

	if ( empty( $variation_data ) ) {

		return $parsed_block;

	}

	/*

	 * Recursively resolve any ref values with the appropriate value within the

	 * theme_json data.

	 */

	wp_resolve_block_style_variation_ref_values( $variation_data, $theme_json );

	$variation_instance = wp_create_block_style_variation_instance_name( $parsed_block, $variation );

	$class_name         = "is-style-$variation_instance";

	$updated_class_name = $parsed_block['attrs']['className'] . " $class_name";

	/*

	 * Even though block style variations are effectively theme.json partials,

	 * they can't be processed completely as though they are.

	 *

	 * Block styles support custom selectors to direct specific types of styles

	 * to inner elements. For example, borders on Image block's get applied to

	 * the inner `img` element rather than the wrapping `figure`.

	 *

	 * The following relocates the "root" block style variation styles to

	 * under an appropriate blocks property to leverage the preexisting style

	 * generation for simple block style variations. This way they get the

	 * custom selectors they need.

	 *

	 * The inner elements and block styles for the variation itself are

	 * still included at the top level but scoped by the variation's selector

	 * when the stylesheet is generated.

	 */

	$elements_data = $variation_data['elements'] ?? array();

	$blocks_data   = $variation_data['blocks'] ?? array();

	unset( $variation_data['elements'] );

	unset( $variation_data['blocks'] );

	_wp_array_set(

		$blocks_data,

		array( $parsed_block['blockName'], 'variations', $variation_instance ),

		$variation_data

	);

	$config = array(

		'version' => WP_Theme_JSON::LATEST_SCHEMA,

		'styles'  => array(

			'elements' => $elements_data,

			'blocks'   => $blocks_data,

		),

	);

	// Turn off filter that excludes block nodes. They are needed here for the variation's inner block types.

	if ( ! is_admin() ) {

		remove_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );

	}

	// Temporarily prevent variation instance from being sanitized while processing theme.json.

	$styles_registry = WP_Block_Styles_Registry::get_instance();

	$styles_registry->register( $parsed_block['blockName'], array( 'name' => $variation_instance ) );

	$variation_theme_json = new WP_Theme_JSON( $config, 'blocks' );

	$variation_styles     = $variation_theme_json->get_stylesheet(

		array( 'styles' ),

		array( 'custom' ),

		array(

			'include_block_style_variations' => true,

			'skip_root_layout_styles'        => true,

			'scope'                          => ".$class_name",

		)

	);

	// Clean up temporary block style now instance styles have been processed.

	$styles_registry->unregister( $parsed_block['blockName'], $variation_instance );

	// Restore filter that excludes block nodes.

	if ( ! is_admin() ) {

		add_filter( 'wp_theme_json_get_style_nodes', 'wp_filter_out_block_nodes' );

	}

	if ( empty( $variation_styles ) ) {

		return $parsed_block;

	}

	wp_register_style( 'block-style-variation-styles', false, array( 'wp-block-library', 'global-styles' ) );

	wp_add_inline_style( 'block-style-variation-styles', $variation_styles );

	/*

	 * Add variation instance class name to block's className string so it can

	 * be enforced in the block markup via render_block filter.

	 */

	_wp_array_set( $parsed_block, array( 'attrs', 'className' ), $updated_class_name );

	return $parsed_block;

}

/**

 * Ensure the variation block support class name generated and added to

 * block attributes in the `render_block_data` filter gets applied to the

 * block's markup.

 *

 * @see wp_render_block_style_variation_support_styles

 *

 * @since 6.6.0

 * @access private

 *

 * @param  string $block_content Rendered block content.

 * @param  array  $block         Block object.

 *

 * @return string                Filtered block content.

 */

function wp_render_block_style_variation_class_name( $block_content, $block ) {

	if ( ! $block_content || empty( $block['attrs']['className'] ) ) {

		return $block_content;

	}

	/*

	 * Matches a class prefixed by `is-style`, followed by the

	 * variation slug, then `--`, and finally a hash.

	 *

	 * See `wp_create_block_style_variation_instance_name` for class generation.

	 */

	preg_match( '/\bis-style-(\S+?--\w+)\b/', $block['attrs']['className'], $matches );

	if ( empty( $matches ) ) {

		return $block_content;

	}

	$tags = new WP_HTML_Tag_Processor( $block_content );

	if ( $tags->next_tag() ) {

		/*

		 * Ensure the variation instance class name set in the

		 * `render_block_data` filter is applied in markup.

		 * See `wp_render_block_style_variation_support_styles`.

		 */

		$tags->add_class( $matches[0] );

	}

	return $tags->get_updated_html();

}

/**

 * Enqueues styles for block style variations.

 *

 * @since 6.6.0

 * @access private

 */

function wp_enqueue_block_style_variation_styles() {

	wp_enqueue_style( 'block-style-variation-styles' );

}

// Register the block support.

WP_Block_Supports::get_instance()->register( 'block-style-variation', array() );

add_filter( 'render_block_data', 'wp_render_block_style_variation_support_styles', 10, 2 );

add_filter( 'render_block', 'wp_render_block_style_variation_class_name', 10, 2 );

add_action( 'wp_enqueue_scripts', 'wp_enqueue_block_style_variation_styles', 1 );

/**

 * Registers block style variations read in from theme.json partials.

 *

 * @since 6.6.0

 * @access private

 *

 * @param array $variations Shared block style variations.

 */

function wp_register_block_style_variations_from_theme_json_partials( $variations ) {

	if ( empty( $variations ) ) {

		return;

	}

	$registry = WP_Block_Styles_Registry::get_instance();

	foreach ( $variations as $variation ) {

		if ( empty( $variation['blockTypes'] ) || empty( $variation['styles'] ) ) {

			continue;

		}

		$variation_name  = $variation['slug'] ?? _wp_to_kebab_case( $variation['title'] );

		$variation_label = $variation['title'] ?? $variation_name;

		foreach ( $variation['blockTypes'] as $block_type ) {

			$registered_styles = $registry->get_registered_styles_for_block( $block_type );

			// Register block style variation if it hasn't already been registered.

			if ( ! array_key_exists( $variation_name, $registered_styles ) ) {

				register_block_style(

					$block_type,

					array(

						'name'  => $variation_name,

						'label' => $variation_label,

					)

				);

			}

		}

	}

}